Implications of New Radiobiological Insights for the Long Term Management of High Level Radioactive Waste

The IAEA has laid down nine principles of radioactive waste management [1], the first of which covers the protection of human health and demands that radioactive waste will be managed in such a way as to provide an acceptable level of protection. The fourth principle demands that future generations are protected in terms of the level of predicted impacts at the same level of protection as applies today. Recent developments in the understanding of the effects of ionising radiation, particularly at low doses and especially for some of the radiation qualities that characterise long lived components of radioactive waste, suggest that there may have been an underestimation of the predicted impact on health of future generations should radioactive waste products reach the biosphere. This could undermine the existing management framework upon which radiological protection is based and may lead to violation of the fourth principle. This paper addresses, from an “in principle†perspective, the issues that new radiobiological evidence and recent developments in biology and genetics have raised in the context of determining radiological risk from internal contamination. Special emphasis is placed on radiation qualities, low energy beta particles, Auger electrons and alpha particles, which characterise the nuclides that are associated with long-lived radioactive decay processes. While absorbed tissue dose remains a guide to one aspect of the risks incurred by exposure (called herein type A risk), evidence is accumulating that other cellular processes may contribute to additional risk (type B risk). These processes are the induction of genomic instability and the bystander effect. Risk assessment in these cases cannot readily and convincingly be based on absorbed tissue dose and require addressing at the levels of the individual cell and the specific track structural features of the different radiation qualities. A potential framework for assessing type B risk is proposed. It is concluded that there is no basis to assume other than that the linear no threshold (LNT) hypothesis will apply to risks (types A and B) from exposure to environmental radioactivity deriving from leakage of buried radioactive wastes.